The invention relates to a hydraulic pile driver including a housing having an impact weight mounted therein for reciprocating movement, said impact weight being fastened to a piston movable in a cylinder, a supply source for liquid under pressure, a supply conduit communicating with said supply source, a liquid discharge conduit, means for alternatively connecting the said supply and discharge conduits to a cylinder chamber at one side of the piston, whereby said piston can be moved by the liquid under pressure in a direction opposite to the direction of movement of the impact weight during the work stroke, the said cylinder chamber during the work stroke of the impact weight being connected to the liquid discharge conduit.
Known embodiments of such hydraulic pile drivers have the disadvantage that when a pile or the like is driven into the ground under an acute angle with the horizontal plane, the maximum impact energy will considerably decrease due to decrease of the acceleration force on the impact weight and an increase of the occurring frictional forces. In practice, the known pile drivers therefore are not capable of driving under a small angle with the horizontal plane, for example under an angle &lt;30.degree., or of driving horizontally, though the latter operation would be often desirable for driving ground anchors, for example.